#!/usr/bin/env python3
# -*- coding: utf-8 -*-

__author__ = 'caogh'
import asyncio,logging

import aiomysql

def log(sql,args=()):
        logging.info('SQL:%s' %sql)

async def create_pool(loop,**kw):
    logging.info('create database connection pool...')
    global __pool
    print('**********************')
    __pool = await aiomysql.create_pool(
        host=kw.get('host','47.105.43.9'),
        port=kw.get('port',3306),
        user=kw['user'],
        password=kw['password'],
        db=kw['db'],
        charset=kw.get('charset','utf8'),
        autocommit=kw.get('autocommit',True),
        maxsize=kw.get('maxsize',10),
        minsize=kw.get('minsize',1),
        loop=loop
    )

async def select(sql,args,size=None):
    log(sql,args)
    global __pool
    async with __pool.get() as conn:
        async with conn.cursor(aiomysql.DictCursor) as cur:
            await cur.execute(sql.replace('?','%s'),args or ())
            if size:
                rs = await cur.fetchmany(size)
            else:
                rs = await cur.fetchall()

        logging.info('rows returned: %s' % len(rs))
        return rs

async def execute(sql,args,autocommit=True):
    log(sql)
    async with __pool.get() as conn:
        if not autocommit:
            await conn.begin()
        try:
            async with conn.cursor(aiomysql.DictCursor) as cur:
                await cur.execute(sql.replace('?','%s'),args)
                affected = cur.rowcount
            if not autocommit:
                await conn.commit()
        except BaseException as e:
            if not autocommit:
                await conn.rollback()
            raise
        return affected

def create_args_string(num):
    L = []
    for n in range(num):
        L.append('?')
    return ', '.join(L)

class Field(object):

    def __init__(self,name,column_type, primary_key, default):
        self.name = name
        self.column_type = column_type
        self.primary_key = primary_key
        self.default = default

    def __str__(self):
        return '<%s, %s:%s>' %(self.__class__.__name__, self.column_type, self.name)


class StringField(Field):

    def __init__(self,name=None, primary_key=False,default=None,ddl='varchar(100)'):
        super().__init__(name,ddl,primary_key,default)


class BooleanField(Field):

    def __init__(self, name=None,default=False):
        super().__init__(name,'boolean',False,default)

class IntegerField(Field):

    def __init__(self,name=None,primary_key=False,default=0):
        super().__init__(name,'bigint',primary_key,default)

class FloatField(Field):

    def __init__(self,name=None,primary_key=False,default=0.0):
        super().__init__(name,'real',primary_key,default)

class TextField(Field):

    def __init__(self,name=None,default=None):
        super().__init__(name,'text',False,default)

class ModelMetaclass(type):

    def __new__(cls, name, bases, attrs):
        if name=='Model':
            return type.__new__(cls,name,bases,attrs)
        tableName = attrs.get('__table__',None) or name
        logging.info('found model: %s (table:%s)' % (name,tableName))
        mappings = dict()
        fields = []
        primaryKey = None
        for k,v in attrs.items():
            if isinstance(v, Field):
                logging.info(' found mapping: %s ==> %s' %(k,v))
                mappings[k] = v
                if v.primary_key:
                    #找到主键
                    if primaryKey:
                        raise Exception('Duplicate primary key for field: %s' % k)
                    primaryKey = k
                else:
                    fields.append(k)
        if not primaryKey:
            raise Exception('Primary key not found.')
        for k in mappings.keys():
            attrs.pop(k)
        escaped_fields = list(map(lambda f: '`%s`' %f,fields))
        attrs['__mappings__'] = mappings #保存属性和列的映射关系
        attrs['__table__'] = tableName
        attrs['__fields__'] = fields  # 除主键外的属性名
        attrs['__select__'] = 'select `%s`, %s from `%s`' % (primaryKey, ', '.join(escaped_fields), tableName)
        attrs['__insert__'] = 'insert into `%s` (%s, `%s`) values (%s)' % (
        tableName, ', '.join(escaped_fields), primaryKey, create_args_string(len(escaped_fields) + 1))
        attrs['__update__'] = 'update `%s` set %s where `%s`=?' % (
        tableName, ', '.join(map(lambda f: '`%s`=?' % (mappings.get(f).name or f), fields)), primaryKey)
        attrs['__delete__'] = 'delete from `%s` where `%s`=?' % (tableName, primaryKey)
        return type.__new__(cls, name, bases, attrs)

class Model(dict, metaclass=ModelMetaclass):

    def __init__(self,**kw):
        super(Model,self).__init__(**kw)

    def __getattr__(self, key):
        try:
            return self[key]
        except KeyError:
            raise AttributeError(r"'Model' object has no attribute '%s'" % key)

    def __setattr__(self, key, value):
        self[key] = value

    def getValue(self, key):
        return getattr(self,key,None)

    def getValueOrDefault(self,key):
        value = getattr(self,key,None)
        if value is None:
            field = self.__mappings__[key]
            if field.default is not None:
                value = field.default() if callable(field.default) else field.default
                logging.debug('using default value for %s:%s' % (key, str(value)))
                setattr(self,key,value)
        return value

    @classmethod
    async def findAll(cls,where=None,args=None,**kw):
        ' find objects by where clause.'
        sql = [cls.__select__]
        if where:
            sql.append('where')
            sql.append(where)
        if args is None:
            args = []
        orderBy = kw.get('orderBy', None)
        if orderBy:
            sql.append('order by')
            sql.append(orderBy)
        limit = kw.get('limit', None)
        if limit is not None:
            sql.append('limit')
            if isinstance(limit,int):
                sql.append('?')
                args.append(limit)
            elif isinstance(limit,tuple) and len(limit) == 2:
                sql.append('?,?')
                args.extend(limit)
            else:
                raise ValueError('Invalid limit value: %s' % str(limit))
        print(sql)
        rs = await select(' '.join(sql),args)
        return [cls(**r) for r in rs]

    @classmethod
    async def findNumber(cls,selectField,where=None,args=None):
        'find number by select and where'
        sql = ['select %s _num_ from `%s`' %(selectField,cls.__table__)]
        if where:
            sql.append('where')
            sql.append(where)
        rs = await select(' '.join(sql),args,1)
        if len(rs) == 0:
            return None
        return rs[0]['_num_']

    @classmethod
    async def find(cls,pk):
        'find object by primary key'
        rs = await select('%s where `%s` = ?' % (cls.__select__,cls.primary_key__),[pk], 1)
        if len(rs) == 0:
            return None
        return cls(**rs[0])

    async def save(self):
        args = list(map(self.getValueOrDefault,self.__fields__))
        args.append(self.getValueOrDefault(self.__primary_key__))
        rows = await execute(self.__insert__,args)
        if rows != 1:
            logging.warn('failed to insert record: affected rows: %s' % rows)

    async def update(self):
        args = list(map(self.getValue, self.__fields__))
        args.append(self.getValueOrDefault(self.__primary_key__))
        rows = await execute(self.__update__, args)
        if rows != 1:
            logging.warn('failed to update by primary key: effected rows: %s' % rows)
    async def remove(self):
        args = [self.getValue(self.__primary_key__)]
        rows = await execute(self.__delete__,args)
        if rows != 1:
            logging.warn('failed to remove by primary key: affected rows: %s' %rows)